android/a2dp: Fix freeing preset on SEP close
android/a2dp: Fix freeing preset on SEP close

In case SEP was opened from local side, corresponding a2dp_setup
structure has just reference to a2dp_preset which is stored on presets
list. As a result, when closing SEP such preset will be freed leaving
dangling pointer on presets list.

silent-snowman/bluez,pstglia/external-bluetooth-bluez,mapfau/bluez,pkarasev3/bluez,ComputeCycles/bluez,ComputeCycles/bluez,silent-snowman/bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez,mapfau/bluez,ComputeCycles/bluez,silent-snowman/bluez,pkarasev3/bluez,mapfau/bluez,pkarasev3/bluez,pstglia/external-bluetooth-bluez,silent-snowman/bluez,pstglia/external-bluetooth-bluez,mapfau/bluez,pkarasev3/bluez